60” Water Transmission Main Improvements

Client: Pittsburgh Water and Sewer Authority (PWSA)

The Challenge

An existing 60-inch diameter riveted steel water line approximately 10,000 feet in length serves PWSA customers and provides a back-up feed to the Fox Chapel Water Authority. This line was installed around 1905 and required refurbishment or replacement to insure integrity of service. Chester was contracted to investigate, design and implement a project to refurbish the line to avoid a costly and disruptive total replacement of the line. Furthermore, Chester was also challenged to complete the design within two months to take advantage of available low interest PENNVEST loan monies that were not likely to be available in later funding cycles.

The Interdisciplinary Approach

Chester’s long-term knowledge of the existing PWSA water system and our extensive experience with cement lining techniques (gunite) allowed us to design the project in an efficient manner and meet the demanding project schedule. The design included cement lining of approximately 10,000 linear feet of 60-inch diameter riveted steel pipe. To ensure customers being served from this line did not see an interruption in service, the design also included approximately 1 mile of temporary water line and service connections. The temporary piping design included special fittings to allow the fire department to connect to them in the event of a fire thus insuring adequate fire protection during the duration of the project. Finally, the design included installation of a 48-inch gate valve past the vast majority of customers served from this line to minimize disruption to the system in the future should the line need to be isolated for maintenance or repair.

The Sustainable Result

Based upon the design, PWSA received a $3.0 million loan and construction work was completed in less than 16 months and within budget. The temporary service connections were utilized to minimize service disruption to customers and maintaining fire protection capabilities during the duration of the project.

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Project Highlights:

Cement lining of approximately 10,000 feet of a 60” steel riveted water line that was installed around 1905.

Installation of ~1 mile of temporary water services to minimize service disruption.